The present invention relates to a metallocene catalyst system for preparing high molecular weight copolymers, and also relates to high molecular weight copolymers and an economical and environmentally friendly process for their preparation.
In the copolymerization of olefins it is possible to obtain, depending on the process procedure, random copolymers having a low content of comonomers, copolymers having a random or blocked structure and a higher incorporation of comonomers than the random copolymers or copolymer rubber having a comonomer content of significantly above 20% by weight based on the total polymer. The copolymers have different properties and different contents of comonomers. Random copolymers are generally distinguished from the corresponding homopolymers by a lower crystallinity, a lower melting point and a lower hardness. A highly random chain structure is desirable for the random copolymers. The olefin copolymers known in the prior art, which are prepared with the aid of heterogeneous Ziegler catalysts, can only meet this requirement to a very limited extent.
EP-A-263 718 describes random C2/C3/Cn terpolymers, where n greater than 3, which are obtained by means of heterogeneous Ziegler catalysts. The C3 content is from 97 to 86 mol %, the C2 content from 0.5 to 6 mol % and the Cn content (n greater than 3) from 2 to 13 mol %. The material has good hot sealing properties but is obtained in a two-stage process using a suspension polymerization step and a gas-phase polymerization step. In order to achieve the desired antiblocking properties, a terpolymer having a high proportion of foreign monomer has to be prepared. However, bipolymers are desirable since these are easier to handle and have a more chemically uniform chain structure.
EP-A-74 194 discloses random C2/C3 copolymers which are prepared by the suspension process. To obtain the desired property profile, the polymers obtained have to be degraded. A high C2 content is necessary to temper the chemical nonuniformity of a heterogeneous catalyst system. The nonuniformity leads to a higher proportion of low molecular weight, readily soluble, high ethylene content fractions in the polymer and thus to restricted utility in the food packaging sector.
JP-A 62-212 707 discloses an ethylene-propylene copolymer having a high ethylene content and a process for its preparation. The process is carried out using ethylenebisindenylzirconium dichloride at a temperature of less than xe2x88x9210xc2x0 C. and is thus not suitable for industrial manufacture. In addition, the activity of the catalyst is very low.
EP-A 485 822 discloses the use of metallocenes substituted in the 2 position on the indenyl ligand for preparing copolymers. EP-A-0 629 632 and EP-A-0 576 970 describe the use of metallocene substituted in the 2 and 4 positions on the indenyl ligand. It is common to these very effective systems that they enable a good random comonomer incorporation to be realized, but that they do not enable preparation of a high molecular weight copolymer if a relatively high ethylene content is simultaneously sought. Random copolymers having high ethylene contents are preferred particularly in application areas in which a high molar mass is required. This applies particularly in deep-drawing applications, blow molding and in the case of films for the packaging sector. Sealing films are particular examples. Furthermore, a low proportion of extractable material is particularly necessary in the food packaging sector. In the case of a relatively high comonomer incorporation, this can be achieved only by a copolymer molding composition having a relatively high molecular weight. Relatively high transparencies are likewise demanded, which likewise requires a relatively high comonomer content in the polymer. Good processability of such a polymer likewise necessitates higher molar masses than can be obtained at industrially relevant polymerization temperatures of from 60 to 80xc2x0 C. using the known metallocenes of the prior art.
The best known metallocenes hitherto, namely representatives of a group having indenyl ligands substituted in the 2 and 4 positions, meet this molar mass target with VN values of about 300 cm3/g and comonomer contents of below 2% by weight, but these comonomer contents are not sufficient to meet the property profile required of good copolymers. This necessitates higher comonomer contents in which case, for the polymers which are prepared using these metallocenes, the viscosity number (VN) very rapidly drops to values of 200 cm3/g and is thus too low. Processability, usability and amount of low molecular weight fractions are then in a range which rules out useful application.
The deficiencies are even clearer in the case of copolymers which are described as rubbers. They contain significantly more than 20% by weight, preferably from 30 to 60% by weight, of xcex1-olefin comonomer, possibly up to 10% by weight of a third xcex1-olefin or diene. Up to now, there is no known metallocene by means of which such a polymer molding composition having a VN of above 200 cm3/g can be produced at industrially realistic process temperatures ( greater than 50xc2x0 C.).
It is an object of the present invention to provide a catalyst component and a catalyst system for preparing high molecular weight copolymers and also provide high molecular weight copolymers and an economical and environmentally friendly process for their preparation.
The object of the present invention is achieved by a catalyst component for preparing a high molecular weight copolymer, which catalyst component is a compound of the formula I 
where
M1 is a metal of group IVb, Vb or VIb of the Periodic Table,
R1 and R2 are identical or different and are each a hydrogen atom, a C1-C10-alkyl group, a C1-C10-alkoxy group, a C6-C10-aryl group, a C6-C10-aryloxy group, a C2-C10-alkenyl group, a C7-C40-arylalkyl group, a C7-C40-alkylaryl group, a C8-C40-arylalkenyl group, an OH group or a halogen atom,
the radicals R3 are identical or different and are each a halogen atom, a C1-C20-hydrocarbon group such as a C1-C10-alkyl group, a C1-C10-alkenyl group, a C6-C10-aryl group or a NR162xe2x80x94, xe2x80x94SR16, xe2x80x94OSiR163, xe2x80x94SiR163 or PR162 radical, where R16 is a halogen atom, a C1-C10-alkyl group or a C6-C10-aryl group, R4 to R12 are identical or different and are as defined for R3 or two or more adjacent radicals R4 to R12 together with the atoms connecting them form one or more aromatic or aliphatic rings, or the radicals R5 and R8 or R12 together with the atoms connecting them form an aromatic or aliphatic ring, R4 to R12 may also be hydrogen and one or more radicals R8, R9, R10, R11 or R12 are different from hydrogen when the radicals R5, R6 and R7 are hydrogen,
R13 is 
xe2x95x90BR14, xe2x95x90AIR14, xe2x80x94Gexe2x80x94, xe2x80x94Oxe2x80x94, xe2x80x94Sxe2x80x94, xe2x95x90SO, xe2x95x90SO2, xe2x95x90NR14, xe2x95x90CO, xe2x95x90PR14 or xe2x95x90P(O)R14, where R14 and R15 are identical or different and are each a hydrogen atom, a halogen atom, a C1-C10-, in particular C1-C4-alkyl group, a C1-C10-fluoroalkyl, in particular CF3 group, a C6-C10-, in particular C6-C8-aryl group, a C6-C10-fluoroaryl, in particular pentafluorophenyl group, a C1-C10-, in particular C1-C4-alkoxy group, in particular a methoxy group, a C2-C10-, in particular C2-C4-alkenyl group, a C7-C40-, in particular C7-C10-arylalkyl group, a C8-C40-, in particular C8-C12-arylalkenyl group, a C7-C40-, in particular C7-C12-alkylaryl group or R14 and R15 together with the atoms connecting them form a ring and M2 is silicon, germanium or tin.
For compounds of the formula I it is preferred that M1 is zirconium or hafnium.
R1 and R2 are preferably identical and are preferably each a C1-C4-alkyl group or a halogen atom, the radicals R3 are preferably each a C1-C4-alkyl group.
R4 to R12 are identical or different and are preferably each a hydrogen atom or a C1-C4-alkyl group, a C1-C4-alkenyl group or a C6-C10-aryl group, where at least one of the radicals R8, R9, R10, R11 or R12 are different from hydrogen when none of the radicals R5, R6 and R7 are different from hydrogen. Preferably, at least two of the radicals R8, R9, R10, R11 or R12 are different from hydrogen when the radicals R5, R6 and R7 are hydrogen. Particularly preferably, two or more adjacent radicals R8, R9, R10, R11 or R12 form one or more aromatic or aliphatic rings.
The radicals R3 are identical or different and are each a C1-C10-alkyl group which may be halogenated, a C1-C10-alkenyl group which may be halogenated, a C6-C10-aryl group which may be halogenated.
The radicals R13 are preferably 
where M2 is silicon or germanium and R14 and R15 are identical or different and are each a C1-C4-alkyl group or a C6-C10-aryl group. R14 and R15 are identical or different and are preferably each a C1-C4-alkyl group, in particular a methyl group, a CF3 group, a C6-C8-aryl group, a pentafluorophenyl group, a C1-C10-, in particular C1-C4-alkoxy group, in particular a methoxy group, a C2-C4-alkenyl group, a C7-C10-arylalkyl group, a C8-C12-arylalkenyl group, a C7-C12-alkylaryl group.
Furthermore, preference is given to compounds of the formula I in which the radicals R4 and R7 are hydrogen and R5 and R6 are each a C1-C4-alkyl group or hydrogen.
Particular preference is given to compounds of the formula I in which M1 is zirconium, R1 and R2 are identical and are each chlorine or a methyl group, the radicals R3 are identical and are each a methyl or ethyl group, R4 and R7 are hydrogen, R5 and R6 are identical or different and are each a C1-C4-alkyl group or hydrogen, at least two of the radicals R8, R9, R10, R11 or R12 are different from hydrogen and form at least one aromatic ring which is preferably 6-membered, and/or R5 or R6 are each a C1-C4-alkyl group when the radicals R8, R9, R10, R11 or R12 are hydrogen, and R13 is 
where M2 is silicon and R14 and R15 are identical or different and are each a C1-C4-alkyl group or a C6-C10-aryl group.
The compounds or types of compounds specified in the Examples are very particularly suitable.
The preparation of the metallocenes I is carried out by literature methods and is shown in the following reaction scheme. 
The 2-phenylbenzyl halide derivatives of the formula A are commercially available or can be prepared by literature methods.
The conversion into the compounds of the formula B is carried out by reaction with substituted malonic esters, under basic conditions, for example in ethanolic solutions of sodium methoxide.
The compounds of the formula B are saponified with alkali metal hydroxides such as potassium hydroxide or sodium hydroxide and decarboxylated by treating the resulting dicarboxylic acids by heating to give the compounds of the formula C.
The ring closure to give the corresponding phenyl-1-indanones of the formula D is carried out by reaction with chlorination reagents such as SOCl2 to give the corresponding acid chlorides and subsequent cyclization using a Friedel-Crafts catalyst in an inert solvent, for example AlCl3 or polyphosphoric acid in methylene chloride or CS2.
The conversion into the 7-phenylindene derivatives of the formula E is carried out by reduction with a hydride-transferring reagent such as sodium borohydride or lithium aluminum hydride or hydrogen and an appropriate catalyst in an inert solvent such as diethyl ether or tetrahydrofuran to give the corresponding alcohols and dehydration of the alcohols under acid conditions, for example using p-toluenesulfonic acid or an aqueous mineral acid, or by reaction with water-withdrawing substances such as magnesium sulfate, anhydrous copper sulfate or molecular sieves.
The preparation of the ligand systems of the formula G and the conversion into the bridged chiral metallocenes of the formula H as well as the isolation of the desired racemic form are known in principle. For this purpose, the phenylindene derivative of the formula E is deprotonated with a strong base such as butyllithium or potassium hydride in an inert solvent and reacted with a reagent of the formula F to form the ligand system of the formula G. This is subsequently deprotonated with two equivalents of a strong base such as butyllithium or potassium hydride in an inert solvent and reacted with the corresponding metal tetrahalide such as zirconium tetrachloride in a suitable solvent. Suitable solvents are aliphatic or aromatic solvents such as hexane or toluene, ether solvents such as tetrahydrofuran or diethyl ether or halogenated hydrocarbons such as methylene chloride or halogenated aromatic hydrocarbons such as o-dichlorobenzene. The separation of the racemic and meso forms is carried out by extraction or recrystallization using suitable solvents.
The derivatization to give the metallocenes of the formula I can be carried out by reaction with alkylating agents such as methyllithium.
The metallocenes I of the invention are highly active catalyst components for olefin copolymerization. The chiral metallocenes are preferably used as the racemate. However, it is also possible to use the pure enantiomer in the (+) or (xe2x88x92) form. The pure enantiomers enable an optically active polymer to be prepared. However, the meso form of the metallocenes should be separated off, since the polymerization-active center (the metal atom) in these compounds is no longer chiral owing to the mirror symmetry at the central metal atom and can therefore not produce a highly isotactic polymer. If the meso form is not separated off, atactic polymer is formed in addition to isotactic polymers. For certain applications, for example soft moldings, this can be thoroughly desirable.
The invention provides a catalyst system comprising a metallocene and a compound which can convert the metallocene into a polymerization-active species. This compound is a cocatalyst.
The catalyst system can also contain a support. The catalyst system can also be prepolymerized. Preference is given to such a supported and prepolymerized embodiment in polymerization processes in which a polymer powder having a high bulk density, uniform particle shape and good handleability in the plant is necessary.
According to the invention, the cocatalyst used is preferably an aluminoxane which preferably has the formula IIa for the linear type and/or the formula IIb for the cyclic type, 
where, in the formulae IIa and IIb, the radicals R17 can be identical or different and are each a C1-C6-alkyl group, a C6-C18-aryl group, benzyl or hydrogen and p is an integer from 2 to 50, preferably from 10 to 35.
The radicals R17 are preferably identical and are methyl, isobutyl, phenyl or benzyl, particularly preferably methyl.
If the radicals R17 are different, they are preferably methyl and hydrogen or alternatively methyl and isobutyl, with hydrogen or isobutyl preferably being present in an amount of up to 0.01 to 40% (number of radicals R17).
The aluminoxane can be prepared in various ways by known methods. One of the methods is, for example, reacting an aluminum hydrocarbon compound and/or a hydridoaluminum hydrocarbon compound with water (gaseous, solid, liquid or boundxe2x80x94for example as water of crystallization) in an inert solvent (for example toluene). To prepare an aluminoxane having different radicals R17, for example two different trialkylaluminums corresponding to the desired composition are reacted with water.
The precise three-dimensional structure of the aluminoxanes IIa and IIb is not known.
Regardless of the method of preparation, all aluminoxane solutions have in common a varying content of unreacted aluminum starting compound which is present in free form or as adduct.
It is possible to preactivate the metallocene by means of an aluminoxane, in particular one of the formula IIa and/or IIb, prior to use in the polymerization reaction. This significantly increases the polymerization activity and improves the particle morphology. The preactivation of the transition metal compound is carried out in solution. For the preactivation, the metallocene is preferably dissolved in a solution of the aluminoxane in an inert hydrocarbon. Suitable inert hydrocarbons are aliphatic or aromatic hydrocarbons. Preference is given to using toluene.
The concentration of the aluminoxane in the solution is in the range from about 1% by weight to the saturation limit, preferably from 5 to 30% by weight, in each case based on the total amount of solution. The metallocene can be used in the same concentration, but it is preferably used in an amount of 10xe2x88x924xe2x88x921 mol per mol of aluminoxane. The preactivation takes from a few seconds to 60 hours, preferably from 1 to 60 minutes. It is carried out at a temperature of from xe2x88x9278 to 100xc2x0 C., preferably from 0 to 70xc2x0 C.
A prepolymerization can be carried out with the aid of the metallocene. For the prepolymerization, preference is given to using at least one of the olefins used in the polymerization.
The metallocene can also be applied to a support. Suitable support materials are, for example, silica gels, aluminum oxides, solid aluminoxane or other inorganic support materials such as magnesium chloride. Another suitable support material is a polymer powder, in particular polyolefin powder in finely divided form.
The cocatalyst, e.g. the aluminoxane, is preferably applied to a support such as silica gel, aluminum oxide, solid aluminoxane, another inorganic support material or else a polyolefin powder in finely divided form and then reacted with the metallocene. Alternatively, the metallocene and the cocatalyst are dissolved in a suitable solvent and then applied to the support. The solvent can then be removed again.
As inorganic supports, it is possible to use oxides which have been produced flame-pyrolytically by combustion of element halides in a hydrogenloxygen flame, or can be prepared as silica gels having certain particle size distributions and particle shapes.
The preparation of the supported cocatalyst can be carried out, for example, as described in EP 92 107 331.8 in the following manner in a stainless steel reactor having an explosion-proof design and fitted with a pump circulation system having a pressure rating of 60 bar, with inert gas supply, temperature control by jacket cooling and a second cooling circuit via a heat exchanger on the pump circulation system. The pump circulation system draws in the reactor contents via a connection in the bottom of the reactor by means of a pump and pushes it into a mixer and through a riser line via a heat exchanger back into the reactor. The mixer is configured such that in the inlet section there is a constricted tube cross-section in which the flow velocity increases and into the turbulence zone of which there is conducted, counter to the flow direction, a thin feed line through which, pulsed, a defined amount of water under 40 bar of argon can be fed in in each case. The reaction is monitored by means of a sampler on the pump circuit.
In principle, however, other reactions and industrial embodiments are also suitable.
The above-described reactor having a volume of 16 dm3 is charged with 5 dm3 of decane under inert conditions. 0.5 dm3 (=5.2 mol) of trimethylaluminum are added at 25xc2x0 C. 350 g of silica gel Grace/Davison 948 which have-been dried beforehand at 600xc2x0 C. in an argon fluidized bed are then metered into the reactor through a solids funnel and are homogeneously distributed by means of the stirrer and the pump circulation system. A total amount of 76.5 g of water is introduced into the reactor in portions of 0.1 cm3 every 15 seconds over a period of 3.25 hours. The pressure resulting from the argon and the gases evolved is kept constant at 10 bar by means of a pressure regulating valve. After all the water has been introduced, the pump circulation system is switched off and stirring is continued for 5 hours at 25xc2x0 C.
The supported cocatalyst xe2x80x9cFMAO on SiO2xe2x80x9d prepared in this way is used as a 10% strength suspension in n-decane. The aluminum content is 1.06 mmol of Al per cm3 of suspension. The isolated solid contains 20% by weight of aluminum, the suspension medium containing 0.1% by weight of aluminum.
Further possible ways of preparing a supported cocatalyst are described, for example, in EP 92 107 331.8.
Subsequently, the metallocene of the invention is applied to the supported cocatalyst by stirring the dissolved metallocene with the supported cocatalyst. The solvent is removed and replaced by a hydrocarbon in which both cocatalyst and the metallocene are insoluble.
The reaction to form the supported catalyst system is carried out at a temperature of from xe2x88x9220xc2x0 C. to +120xc2x0 C., preferably 0-100xc2x0 C., particularly preferably from 15 to 40xc2x0 C. The metallocene is reacted with the supported cocatalyst by combining a suspension of from 1 to 40% by weight, preferably from 5 to 20% by weight, of the cocatalyst in an aliphatic, inert suspension medium such as n-decane, hexane, heptane or diesel oil with a solution of the metallocene in an inert solvent such as toluene, hexane, heptane or dichloromethane or with the finely milled solid of the metallocene. The other way around, a solution of the metallocene can also be reacted with the solid of the cocatalyst.
The reaction is carried out by intensive mixing, for example by stirring together at a molar Al/M1 ratio of from 100/1 to 10000/1, preferably from 100/1 to 3000/1, for a reaction time of from 5 to 600 minutes, preferably from 10 to 120 minutes, particularly preferably from 10 to 60 minutes, under inert conditions.
During the course of the reaction time for preparing the supported catalyst system, particularly when using metallocenes of the invention having absorption maxima in the visible region, changes occur in the color of the reaction mixture and these color changes enable the progress of the reaction to be monitored.
After the reaction time has elapsed, the supernatant solution is separated off, for example by filtration or decantation. The remaining solid can be washed from 1 to 5 times with an inert suspension medium such as toluene, n-decane, hexane, diesel oil or dichloromethane for removing the soluble constituents in the catalyst formed, in particular for removing unreacted and therefore soluble metallocene.
The supported catalyst system thus prepared can be resuspended as vacuum-dried powder or while still moist with solvent and metered as a suspension in an inert suspension medium into the polymerization system. Inert suspension media are the abovementioned suspension media or wax-like hydrocarbons.
According to the invention, other suitable cocatalysts which can be used in place of or in addition to an aluminoxane are compounds of the formulae R18XNH4xe2x88x92xBR194, R18XPH4xe2x88x92xBR194, R183CBR194, BR193. In these formulae, x is a number from 1 to 4, preferably 3, the radicals R18 are identical or different, preferably identical, and are C1-C10-alkyl, C6-C18-aryl or 2 radicals R18 together with the atoms connecting them form a ring and the radicals R19 are identical or different, preferably identical, and are C6-C18-aryl which can be substituted by alkyl, haloalkyl or fluorine.
In particular, R18 is ethyl, propyl or phenyl and R19 is phenyl, pentafluorophenyl, 3,5-bistrifluoromethylphenyl, mesityl, xylyl or tolyl (cf. EP-A 277 003, EP-A 277 004 and EP-A 426 638).
When using the abovementioned cocatalysts, the actual (active) polymerization catalyst is the reaction product of the metallocene and at least one of the cocatalysts. For this reason, this reaction product is preferably first prepared outside the polymerization reactor in a separate step using a suitable solvent.
According to the invention, a suitable cocatalyst is in principle any compound which, owing to its Lewis acidity, can convert the neutral metallocene into a cation and stabilize the latter (xe2x80x9clabile coordinationxe2x80x9d). In addition, the cocatalyst or the anion formed therefrom should undergo no further reactions with the metallocene cation formed (cf. EP-A 427 697).
To remove catalyst poisons present in the olefin monomer, purification using an aluminum alkyl, for example trimethylaluminum, triisobutylaluminum or triethylaluminum, is advantageous. This purification can be carried out either in the polymerization system itself or the olefin is brought into contact with the Al compound and subsequently separated off again before addition to the polymerization system.
The invention provides a copolymer having a viscosity number (VN) greater than 200 cm3/g, preferably  greater than 250 cm3/g and particularly preferably  greater than 300 cm3/g. The copolymer of the invention comprising from 99.5 to 30% by weight, based on the total polymer, of propylene units, preferably from 98.5 to 40% by weight, particularly preferably from 97.5 to 50% by weight, of propylene units. Correspondingly, the contents of comonomer units are from 0.5 to 70% by weight, preferably from 1.5 to 60% by weight and particularly preferably from 2.5 to 50% by weight. The comonomer units are derived from ethylene or olefins having at least 4 carbon atoms and the formula Raxe2x80x94CHxe2x95x90xe2x80x94CHxe2x80x94Rb, where Ra and Rb are identical or different and are each a hydrogen atom or a hydrocarbon radical having from 1 to 15 carbon atoms, for example a C1-C15-alkyl radical, or Ra and Rb together with the carbon atoms connecting them form a ring having from 4 to 12 carbon atoms. Examples of such comonomers are 1-olefins such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene or ethylidenenorbornene.
Very particularly preferably, random copolymers are composed of from 1.5 to 15% by weight of comonomer and from 98.5 to 85% by weight of propylene, while rubbers have comonomer contents of from 20 to 60% by weight and propylene contents of from 80 to 40% by weight. Terpolymers can additionally contain up to 10% by weight, preferably up to 5% by weight, of the diene component.
Such rubbers or terpolymers have viscosity numbers (VN) of  greater than 200 cm3, preferably  greater than 250 cm3 and particularly preferably  greater than 300 cm3/g. Random copolymers having C2 contents of  greater than 4% by weight have VN values of  greater than 250 cm3/g and preferably  greater than 300 cm3/g. Random copolymers having C2 contents of from 1.5 to 4% by weight have VN values of  greater than 350 cm3/g.
The invention also provides a process for preparing a copolymer. For this purpose, polymerization can be carried out at a temperature of from 50 to 200xc2x0 C., preferably from 55 to 150xc2x0 C., particularly preferably from 60 to 150xc2x0 C., at a pressure of from 0.5 to 100 bar, preferably from 2 to 80 bar, particularly preferably from 20 to 64 bar, in solution, in suspension or in the gas phase, in one or more stages, in the presence of the catalyst system of the invention.
The copolymerization can be carried out in solution, in suspension or in the gas phase, continuously or batchwise, in one or more stages at a temperature of from 50 to 200xc2x0 C., preferably from 5 to 150xc2x0 C., particualrly preferably from 60 to 150xc2x0 C. Monomers which are copolymerized are propylene and olefins derived from ethylene or olefins having at least 4 carbon atoms and the formula Raxe2x80x94CHxe2x95x90CHxe2x80x94Rb, where Ra and Rb are identical or different and are each a hydrogen atom or a hydrocarbon radical having from 1 to 15 carbon atoms, for example an alkyl radical, or Ra and Rb together with the carbon atoms connecting them form a ring having from 4 to 12 carbon atoms. Other olefins which can be used are dienes, in which case Ra or Rb is a C2-C12-alkene and Ra and Rb can here too also be joined to form a ring. Examples of such dienes are the ethylidenenorbornene, norbornadiene, dicyclopentadiene, 1,4-hexadiene or butadiene. Preference is given to using such dienes for copolymerization with propylene and a further olefin.
Examples of olefins as comonomers are 1-olefins such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, norbornene. Preference is given to polymerizing propylene and ethylene, in the case of the preparation of a terpolymer preference is given to polymerizing propylene, ethylene and ethylidenenorbornene.
As molecular weight regulator and/or to increase the activity, hydrogen can be added if required. The total pressure in the polymerization system is from 0.5 to 100 bar. Preference is given to carrying out the polymerization in the industrially particularly interesting pressure range of from 5 to 64 bar. Here, the metallocene is employed in a concentration, based on the transition metal, of from 10xe2x88x923 to 10xe2x88x928 mol, preferably from 10xe2x88x924 to 10xe2x88x927 mol, of transition metal per dm3 of reactor volume. The aluminoxane is used in a concentration of from 10xe2x88x925 to 10xe2x88x921 mol, preferably from 10xe2x88x924 to 10xe2x88x922 mol, per dm3 of solvent or per dm3 of reactor volume. The other cocatalysts mentioned are used in approximately equimolar amounts to the metallocene. However, higher concentrations are also possible in principle.
When the polymerization is carried out as a suspension or solution polymerization, an inert solvent customary for the Ziegler low-pressure process is used. For example, the polymerization is carried out in an aliphatic or cycloaliphatic hydrocarbon, for example propane, butane, hexane, heptane, isooctane, cyclohexane, methylcyclohexane. It is also possible to use a petroleum or hydrogenated diesel oil fraction. Toluene can also be used. Preference is given to carrying out the polymerization in the liquid monomer.
If inert solvents are used, the monomers are metered in in gaseous or liquid form.
The polymerization time can be any desired, since the catalyst system to be used according to the invention displays only a low time-dependent drop in the polymerization activity.
Before adding the catalyst, in particular the supported catalyst system (comprising the metallocene of the invention and a supported cocatalyst or comprising a metallocene of the invention and an organoaluminum compound on a polymer powder in finely divided form), it is possible to additionally introduce another aluminum alkyl compound such as trimethylaluminum, triethylaluminum, triisobutylaluminum, trioctylaluminum or isoprenylaluminum into the reactor to make the polymerization system inert (for example to remove catalyst poisons present in the olefin). This is added to the polymerization system in a concentration of from 100 to 0.01 mmol of Al per kg of reactor contents. Preference is given to triisobutylaluminum and triethylaluminum in a concentration of from 10 to 0.1 mmol of Al per kg of reactor content. This enables a small Al/M1 molar ratio to be selected in the synthesis of a supported catalyst system.
However, the use of further substances for catalyzing the copolymerization reaction is in principle not required, i.e. the systems of the invention can be used as sole catalyst for olefin copolymerization, in particular no stereo regulators (donors) are necessary.
The process of the invention enables high molecular weight propylene copolymers to be prepared in the industrially particularly interesting temperature range from 65 to 150xc2x0 C. In particular, it makes it possible to obtain high molecular weight random copolymers having a high comonomer content and a high transparency and low proportion of extractable material, and also rubbers which under industrially sensible polymerization temperatures of  greater than 50xc2x0 C. have a very high molar mass and viscosity numbers of  greater than 200 cm3/g.
The invention provides for the use of at least one catalyst component of the invention or at least one catalyst system of the invention for preparing high molecular weight copolymers.
The invention provides for the use of the copolymers of the invention for preparing highly transparent, stiff moldings, in particular by thin-wall injection molding, highly transparent stiff films, high molecular weight rubber having a low glass transition temperature, block copolymers having a high molecular weight and high impact toughness, and high molecular weight random copolymers having low proportions of extractable material for use in the food packaging sector.